Laden with oil, vital fluid of war, Chewaucan cleared Baytown, Tex., 22 March 1945, and reached Pearl Harbor 6 May. Attached to the Hawaiian Sea Frontier she carried oil among the Hawaiian Islands, Midway, Johnston, Canton, and Christmas Islands until 16 June 1946 when she sailed for San Pedro, arriving 25 June.

Between 23 September 1946 and 4 July 1947, Chewaucan operated out of Seattle on cargo duty to various Alaskan ports, then sailed in the Pacific, calling at Pearl Harbor and Kwajalein and ferrying oil until 6 January 1948. She sailed from San Pedro 8 January 1948 and entered Philadelphia Naval Shipyard 4 February for conversion to a combination oiler-tanker.

Chewaucan put out from Norfolk 7 July 1948 to become one of the original 12 ships of the 6th Fleet in the Mediterranean. Home ported at Naples, Italy, in support of the 6th Fleet, she remained in the Mediterranean except for periodic overhauls in the United States through 1960. Her duty changed from direct replenishment of the 6th Fleet to supplying various shore storage facilities when, on 2 August 1957, she was transferred from the 6th Fleet to Commander, Naval Activities, Italy, for operational control.